The objective of this proposed effort is the development of a periodontal temperature probe which can provide objective and simple assessment of periodontal disease activity. Studies have suggested that inflamed sulci are accompanied by elevated temperature indications. Conventional diagnostic techniques, such as bleeding upon probing, suppuration, or gingival redness are highly subjective. The temperature sensing element is imbedded in the probe tip. The probe is similar to conventional periodontal probes with Williams markings. The advantages are (1) the concurrent measurement of sucular temperature and attachment level, (2) the identical probe insertion technique as conventional attachment level measurement, and (3) the rapidity in allowing for multiple-site evaluation of disease activity. The key feature of this probe which allows the faithful measurement of sulcular temperature is the specially designed low thermal mass of the probe tip. This feature provides minimal thermal perturbation to the regional tissues thus allowing for a measurement accuracy of better than 0.1 degrees C and a response time of less than 0.2 second. These have been demonstrated during the Phase I program. Phase I clinical investigation showed positive correlation with disease activity. The Phase II program will be oriented towards further clinical validation of sulcular temperature changes accompanying disease activity, optimization of the diagnostic parameter, and the integration of the device into a self-contained handheld probe unit. Probes with such special features are not currently available to clinicians. The simplicity of the concept and the similarity in dimensions to a conventional periodontal probe would greatly enhance its eventual marketability.